Answer:
Option C.
Step-by-step explanation:
Non - coplanar : If two lines do not lie on the same plane, then they are called non-coplanar lines.
Parallel lines : If the distance between two lines remains same and they never intersect each other, then they are called parallel lines.
Perpendicular line: If two lines intersect each other and form right angle, then they are called perpendicular lines.
Skew lines : If two lines lie on different plane and do not intersect each other, then they are called skew lines.
From the given figure it is clear that lines a and d lie on the same plane M and form right angle. So, lines a and d are perpendicular.
Therefore, the correct option is C.
